Digital Video Broadcasting-Satellite Multi-Input Receiving Circuit and Associated Method

Abstract

A digital video broadcasting-satellite (DVB-S) multi-input receiving circuit and an associated method are provided to receive satellite input signals provided by a plurality of low noise blocks (LNB), thereby reducing the cost of DVB-S receivers. The DVB-S multi-input receiving circuit includes a selection circuit and a combiner. The selection circuit includes a plurality of signal paths for conveying a plurality of satellite input signals, and enables one of the signal paths to output one of the satellite input signals. The combiner combines the signal paths into a single signal path, which is coupled to a DVB-S tuner.

1 . A digital video broadcasting-satellite (DVB-S) multi-input receiving circuit comprising:
 a selection circuit including a first signal path and a second signal path, the first signal path receiving and conveying a first satellite input signal, the second signal path receiving and conveying a second satellite input signal, wherein the selection circuit enables one of the first signal path and the second signal path according to a control signal to output one of the first satellite input signal and the second satellite input signal; and   a combiner, coupled to the selection circuit, for combining the first signal path and the second signal path into a single signal path, and coupling the single signal path to a DVB-S tuner.   
   
   
       2 . The DVB-S multi-input receiving circuit of  claim 1 , further comprising:
 a control unit for generating the control signal.   
   
   
       3 . The DVB-S multi-input receiving circuit of  claim 2 , wherein the control unit is a microcontroller. 
   
   
       4 . The DVB-S multi-input receiving circuit of  claim 2 , wherein the first satellite input signal and the second satellite input signal are provided by a first low noise block (LNB) and a second LNB respectively, the selection circuit comprises a first switch and a second switch, the control unit provides a power signal to the first LNB and the second LNB via the first switch and the second switch respectively, and the control signal comprises a first enable signal and a second enable signal for respectively controlling the first switch and the second switch. 
   
   
       5 . The DVB-S multi-input receiving circuit of  claim 4 , wherein the selection circuit comprises a first inductor and a second inductor, and the power signal is provided to the first LNB and the second LNB via the first inductor and the second inductor respectively. 
   
   
       6 . The DVB-S multi-input receiving circuit of  claim 5 , wherein the first inductor and the second inductor are trace inductors. 
   
   
       7 . The DVB-S multi-input receiving circuit of  claim 4 , wherein the first switch and the second switch are transistor switches. 
   
   
       8 . The DVB-S multi-input receiving circuit of  claim 1 , wherein the selection circuit comprises a first low noise amplifier (LNA) and a second LNA disposed in the first signal path and the second signal path respectively, wherein the control signal comprises a first enable signal and a second enable signal for enabling the first LNA and the second LNA respectively. 
   
   
       9 . The DVB-S multi-input receiving circuit of  claim 1 , wherein the selection circuit comprises a first capacitor and a second capacitor which are disposed in the first signal path and the second signal path respectively to isolate direct current (DC) signals in the first signal path and the second signal path respectively. 
   
   
       10 . The DVB-S multi-input receiving circuit of  claim 1 , wherein the combiner and the DVB-S tuner are integrated in an integrated circuit (IC). 
   
   
       11 . The DVB-S multi-input receiving circuit of  claim 1 , wherein the DVB-S multi-input receiving circuit and the DVB-S tuner are integrated in an integrated circuit (IC). 
   
   
       12 . The DVB-S multi-input receiving circuit of  claim 1 , wherein a length of the first signal path within the combiner is one quarter a wavelength of the first satellite input signal. 
   
   
       13 . The DVB-S multi-input receiving circuit of  claim 1 , wherein a length of the second signal path within the combiner is one quarter a wavelength of the second satellite input signal. 
   
   
       14 . A digital video broadcasting-satellite (DVB-S) multi-input receiving circuit comprising:
 a radio frequency (RF) switch for receiving a first satellite input signal and a second satellite input signal from a first low noise block (LNB) and a second LNB respectively, and selectively outputting one of the first satellite input signal and the second satellite input signal according to a control signal; and   a control unit for generating the control signal.   
   
   
       15 . The DVB-S multi-input receiving circuit of  claim 14 , wherein the RF switch outputs one of the first satellite input signal and the to second satellite input signal to a DVB-S tuner, and the RF switch and the DVB-S tuner are integrated in an integrated circuit (IC). 
   
   
       16 . The DVB-S multi-input receiving circuit of  claim 14 , wherein the control unit provides a power signal to the first LNB and the second LNB respectively, and the power signal is coupled to the first LNB and the second LNB via a first inductor and a second inductor respectively. 
   
   
       17 . The DVB-S multi-input receiving circuit of  claim 16 , wherein the first inductor and the second inductor are trace inductors. 
   
   
       18 . In a digital video broadcasting-satellite (DVB-S) signal receiving circuit, a control method comprising:
 receiving and conveying a plurality of satellite input signals via a plurality of signal paths;   enabling one of the signal paths according to a control signal; and   combining the signal paths into a single signal path.